CHEMISTRY OF COMMON THINGS 



Sweat Pore 



HAIR 



salt is added when the soap is through cooking. While 

 cooling the soap will rise to the surface and leave the 

 brine, alkali, and glycerine in the solution. Liquid soap is 

 made by adding water to the soft soap until it flows as 

 freely as desired. Liquid soap is more sanitary than hard 

 soap, especially in schools, railroad stations, and other 

 public buildings, as 

 it prevents more 

 than one person 

 from handling the 

 same soap. 



Cheap laundry 

 soaps are made of 

 resin and waste 

 lard, butter, tallow, 

 scraps of meat, 

 waste fat, and kit- 

 chen refuse and an 

 excess of a strong 



base. The excess ffll'/l U W "t 



base makes them 

 very hard on the 

 hands and also on 

 fine fabrics. Fine 

 toilet soaps are made of pure plant oils and enough of 

 the base to make them almost neutral but leave them 

 slightly basic. (Ask your teacher or parents to tell you 

 how your great-grandparents used to prepare potash for 

 soap making.) 



15. How Soap Cleans. The hands, face, and other 

 parts of the body are kept soft by an oil which is secreted 

 by the glands in the skin. When the hands and face are 

 washed several times without soap, as when out camping, 



Cell 



VERTICAL SECTION OF THE SKIN 



Note the relative size of the oil glands. 

 (Magnified.) 



